Today’s one word prompt from The Daily Post is Footsteps. I thought about this for a while and realized that for some people, being able to walk and leave footsteps is a challenge. Not everyone is fortunate enough to have a good set of legs and feet. I know this for a fact because I adopted a wonderful son named Abram who has spina bifida. As a preteen and teenager he was a world class wheel chair athlete, especially in shot-putt , discus, and javelin throwing . He is getting married this year to Maggie, one of his competitors, and I couldn’t be happier for them. The picture is from Maggie’s Facebook photo album.
Part of the science fiction novel I wrote involved the protagonist losing both legs above his knees in a freak accident. My solution to this almost overwhelming problem was to project new technology in the field of prosthetic legs. Below is the chapter in the novel that deals with how these new legs work. I hope this technology comes to pass, and soon.
Chapter 15 – New Legs
When the prosthetic legs arrived, Emily scheduled Sted for surgery. The latest prosthetic devices were attached surgically. Gone were the days of the simple mechanical devices that simulated the missing limb.
Above the biomechanical knee joint was the latest in medical technology. A 3D-printed carbon matrix hollow shaft was designed to slip over the severed femur bone. Then a calcium-based paste containing osteoblast cells from Sted’s original surgery was layered over the matrix to stimulate bone growth. The body, in effect, created its own glue by building bone tissue around the carbon matrix shaft. Once the prosthetic was joined to the bone, it sealed itself in a bond as strong as the original bone.
That was only the first step in the procedure. Next, the severed muscle and nerve tissue in the preserved stump was married, via stem cells, with the specially prepared ligament and electronic fibers in the prosthetic. The electronic fibers were connected to the processor embedded in the lower portion of the prosthetic. This allowed the actions of the lower leg and foot to be programmed to react to the stimuli from the brain through
the nerve/fiber interface.
Just two days after the surgery, Sted was working with his physical therapist, Alice Wheeler, in programming the new legs.
Alice could be very intimidating when she wanted. Her dark hair was pulled back into a bun to keep it out of the way of her work, and her eyes appeared to be almost too big for her face. This may have been due to the startling amount of mascara she wore and her long eyelashes. Regardless of the reason, Sted knew those eyes missed nothing. Now he knew what people meant when they said they felt like they were under a microscope.
They started with simple movements.
“Okay, Captain,” Alice said. “I need you to imagine each simple movement in your head, and then I need you to direct your body to execute that movement. Let’s start with the left foot. I want you to imagine you’re pointing the toe of your left foot toward me. I have initialized the processor in the left leg to read the electronic signal coming through the nerve/fiber interface in your thigh and to react by pointing the toe. Now,
point your left toe at me.”
Sted obeyed just because he had nothing better to do with his life right now. He was sitting on a cushioned table in the PT suite dressed in a light blue form-fitting top and shorts. When he imagined pushing his toes forward and pulling his heel back, the muscles in the thigh reacted ever so slightly to accommodate that motion, and the nerve/fiber interface was stimulated by his brain. The fuzzy electronic signal the processor received
was recorded and associated with pointing the toes.
“Works,” Sted reported laconically as his new foot pointed in a delayed reaction.
Alice nodded as she typed something on the keyboard that was connected to wires leading in to the heel of his left leg. “Now, imagine relaxing the foot. I have programed it to return to its normal position.”
Sted let off on the pushing motion in his mind, and his thigh muscles and nerves reacted again. The movement of the foot back to its normal position was delayed slightly once again as the processor made the association between the fuzzy electronic signal and the desired reaction.
“Okay,” Alice said, “this is a first level association between your body and the prosthetic. When you try to point that foot again and then relax, the reaction should be immediate. Why don’t you go through several repetitions and see if the reaction of the foot seems appropriate to you.”
Sted tried several times to cycle his foot from pointing and then back to relaxed mode. The foot responded immediately this time, though in a somewhat mechanical fashion. He was also surprised that he got feedback from his heel moving against the top of the cushioned table.
“What is that feeling I’m getting of the prosthetic heel moving against the top of this PT table?”
A big smile lit up Alice’s face. “We have built skin-like nerve sensors into the prosthetic that provide feedback to the processor, which slows down the signal enough for the nerve/fiber interface to pass the information back to the brain. It won’t take your brain long to map the returned stimuli to the feelings it got from your original nerve cells that relate to touch.”
“Does that mean I will eventually be able to feel everything my prosthetic legs and feet contact?”
“It is not an exact science at this point,” Alice replied. “The human brain is very adaptive and can usually fool itself into thinking that the returning nerve pulses come from what it thinks are your original legs. It takes time and practice, but we hope you will get the same results as some of our other patients, where the interface becomes almost transparent. We will just have to wait and see how your brain adapts.
“At this point, there is no nuance programmed in for doing this at different speeds, or doing it with or without moving the toes or any of a dozen other variations. We need to program in all of the gross motor movements first. We can program the fine motor movements once we have all of the larger movements settled.”
“Why do you have to connect wires to the processor in the leg?” Sted asked. “Wouldn’t it be easier to do that wirelessly?”
Alice nodded. “Certainly, but how would you like someone to be able to control your new legs against your will with a simple wireless connection? Those leg processors have to be completely isolated and only responsive to your nerve/fiber interface. Once we finish programming your new legs, you will take complete responsibility for your own security. You will password protect the hardwired interface so that even I won’t be able to
change the programming against your will.”
“So, when can I start walking?” Sted asked with the first sign of hope in his voice.
“We can’t begin walking practice until we test out all of the gross motor skills from the knees down. It’s going to take at least two days of trial and error to get all of your gross motor movements programmed. In particular, when we work our way up to knee flexing, we have to be careful with the bonding between the prosthetic and the bones and musculature in the thighs. We don’t want it to tear because we’ve not programmed the reaction of the prosthetic properly. You’re going to have to show some patience.”
Sted sighed. “I’ll follow orders while you do the programming. I really need to feel whole again, and I’m not going to do anything to slow down this process. What’s next? More motions with the left foot, or do we program the toe pointing in the right foot?”
“I’m going to program one leg at a time so you don’t get any ideas of trying to go off walking before you’re ready. I know your type, Captain!” Alice smiled. “We’re going to program rotating the left foot clockwise and counter-clockwise next. Then we go to toe curling and then wiggling your big toe. So, let me enter clockwise rotation. Now, rotate your left foot clockwise without rotating your hip joint. We’re just working on foot movements at this point.”
The two of them worked the entire morning on Sted’s left ankle, foot, and toe movements. Then Emily came back to the lab and placed Sted on his gurney and wheeled him to his room for his lunch break.
Sted hardly noticed the food he was consuming. His emotional state was very fragile, and he felt like his life was at a tipping point. He had been depressed and despondent from the time he first woke up after the accident until he “felt” the heel of his prosthetic move against the top of the PT table. That odd sensation had sparked an insane hope that he
could climb back out of the disaster his life had become.
His life goal had seemed completely beyond his reach until now. But if he could learn to walk with his new legs and even “feel” sensations passed back to his brain from the sensors on the surface of the prosthetic device, then there was no reason to think he could not command a space vessel once again.
But then doubt crept in, and he whipsawed himself back into despair, because he knew that naval regulations prohibited him from commanding a ship. The interstellar ship that was about to be constructed would be under the command of a United Space Navy captain, so how could he possibly gain that position?
By the end of the meal, Sted had reached a decision. He would do everything in his power to get back into a captain’s chair, in or out of the Navy. Once there, he would prove his worthiness despite his injuries. To hell with the regulations! They weren’t written in stone. They could be changed, and he would make every effort to do just that.